I could list other synonyms, perhaps churlish or loutish. The person could also be acerbic, belligerent or acrimonious, pugnacious or rancorous. Again, I almost feel like this is general reference since at most we can offer lists of words from a thesaurus until you remember the "right" one on the tip of your tongue. :)
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ZairjaAug 22 '12 at 13:38

+1 For troll. IMHO this is the best answer to emphasise that the disagreement is only to produce a reaction, not out of genuine belief. Its only problem is that its a pretty modern word, so older readers may not be familiar with it.
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T.E.D.Aug 22 '12 at 14:35

2

The question is tagged with adjectives, but you have given nouns.
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tchristAug 22 '12 at 15:21

@tchrist Agreed, the question is tagged with adjectives, and the details specify adjectives, but the question title implies nouns. As you can see, while my answer emphasizes noun forms it also addresses the adjectival forms.
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Joel BrownAug 22 '12 at 17:53

1

@Jodrell Troll does. If your point is that the others proffered are inferior, I'd agree.
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T.E.D.Aug 23 '12 at 15:14

I'd describe someone as antagonistic if they are the type of person that thrives on disagreement and conflict for its own sake. These are the type of people who will start arguments for the sole purpose of creating a tense, adversarial atmosphere.

This one seems to fit best. It implies disagreement for the purpose of annoying others. +1
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Jon HulkaAug 22 '12 at 22:41

3

I'm not sure how this isn't the top answer--it's by far the best. While troll fits the bill exactly, you can't use it in formal language.
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Ryan AmosAug 23 '12 at 2:25

@JonHulka only if antagonising is synonomous with annoying but, I take your point. More relavently to the question, it is shares meaning with both upsetting and disagreeing so is a good match.
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JodrellAug 23 '12 at 11:34

I'll add 'argumentative' and 'confrontational', since those two haven't been mentioned yet. 'Argumentative' is pretty self-explanatory, being someone who delights in arguing, and similarly 'confrontational' is one who seeks out conflict (presumably because they enjoy it/ need it/ that's how they roll).

I don’t suppose the specific adjective you’re looking for happens to be querulous, is it?

Per the OED, it means:

Complaining, given to complaining, full of complaints, peevish.

Another possibility might be belligerent, which was originally from the Latin for war-making, but now more often means simply combative in a more general sense. There’s also bellicose, which may now carry additional connotations of loudness.

You can find synonyms to these at the links given above. Surely one of those must be your sought-after word. The merged set of suggestions provided by those two links is:

The word 'contrary' may be used to mean exactly what you describe, as in

'Oh, Arch, will you stop being so contrary all the time!'

I, for one, have heard that far too many times as a child.

There is also a poem 'Contrary Larry':

Larry, you are so contrary!
You make me upset.
If I say, "I am starving now",
you're not hungry yet.
If I would like some quiet time.
You go get your drum.
If all I have is candy bars,
all you want is gum.

Larry, you are so contrary!
You drive me insane.
If I say, "I love sunny days",
you say you love the rain.

This was my first thought, too. But "contrary" is generally used to refer to an annoying child. I wouldn't call a contrary child "arrogant", the word used in the question. So it may or may not be what the OP is looking for.
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JayAug 22 '12 at 14:35

the best words that I can find are invective, vitriolic, or taunting. The problem is that I am not sure how familiar it would sound to use these to describe a person. They are more often applied to language or comments. I think that the meaning of "an invective person" would be clear in context but not necessarily immediately or smoothly so.

You might have to go with a multiword phrase, such as "maliciously argumentative" or "always spouting baseless invective". I think that troll is also a good choice but problematic in that I think it is still more strongly associated with behavior on the internet rather than in meatspace and perhaps would suggest this more specific interpretation.

When confronted with someone who was contrarian just to be annoying, or even willfully ignoring the arguments presented by changing definitions on the fly or overemphasizing trivialities, I've often used the term gadfly. This comes from a story Plato wrote about Socrates. In the more charitable scenario, the gadfly is someone who irritates the established order by posing inconvenient or novel questions, but it seemed to be overloaded in practice to include people who were merely irritating because they were arguing from willful ignorance.

Why not disagreeable? This word implies that the one who is disagreeable is so because they have reason(s) to disagree other than a fundamental difference of opinion or philosophy - it implies they are disagreeable for the sake of disagreeing - there is a negative connotation, with undertones of malcontent.

I think the downvotes are due to the fact that the question asks for a word describing one who disagrees for the sole purpose of upsetting other parties. Someone playing Devil's Advocate doesn't necessarily have only that goal in mind.
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user22138Jul 8 '13 at 18:00

Taking a stab at answering... The first word that came to my mind when reading your question was: bigot, bigoted. All definitions were yanked from the Oxford Dictionaries website (the links will lead you to their appropriate definition on the Oxford Dictionaries webiste.).*Note: No online dictionary is superior to another and no dictionary can claim the rights to words. Other dictionaries (like Merriam-Webster OnLine, Collins Online Dictionary, Dictionary.com, Cambridge Dictionaries Online, etc.) are just as good and there are plenty of others on the internet that would say pretty much the same definitions. I wouldn't have been able to make this list, by the way, without the help of Google, which got me to this Wikipedia article.